Cooling cylinder liners of internal combustion engines



April 7, 1964/ D. GIACOSA ETAL 3,127,879

' coouuc CYLINDER LINERS OF INTERNAL COMBUSTION mamas Filed Feb. 5, 19632 Sheets-Sheet 1 Fllg. 7

April 7, 1964 GlACOSA A 3,127,879

COOLING CYLINDER LINERS OF INTERNAL COMBUSTION ENGINES Filed Feb. 5,1965 2 Sheets-Sheet 2 United States Patent 3,127,879 COOLING CYLINDERLINERS OF INTERNAL COMBUSTIUN ENGINES Dante Giacosa and GiovanniTorazza, Turin, Italy, assignors to Fiat Societa per Azioni, Turin,Italy Filed Feb. 5, 1963, Ser. No. 256,341 Claims priority, applicationItaly Feb. 10, 1962 6 t'llaims. (Cl. 123-41.72)

This invention relates to a device for cooling the cylinder liners ofinternal combustion engines by means of the lubricating oil.

An object of this invention is to provide a device which affordsadvantages such as noiseless run of the engine of known water coolingdevices having an opened or pressurized circuit, as well as advantagesof quick reaching of the operational temperature of the air coolingdevices, while avoiding inherent drawbacks of such iknown devices.

In order to be efiicient the lubricating oil for cooling purposes has toflow at a high speed along the surface to be cooled.

The improved cooling device comprises annular interstices of relativelysmall cross section, formed around the cylinders liners, through whichpressure oil derived from a branch of the lubricating circuit iscirculated and then cooled in a cooler.

The cross-sectional area of oil flow should be calculated in such mannerthat at highest engine power the oil speed is between 1 and 2 m./sec.,this being the range within which the mos-t efficient cooling isafforded.

Further characteristic features and advantages of this invention will beunderstood from the appended description referring to the accompanyingdrawings which show an embodiment thereof:

FIGURE 1 is a diagrammatical representation of the cooling device;

FIGURE 2 is a diagrammatical vertical sectional view of a cylinderliner, and

FIGURE 3 shows an enlarged detail of FIG. 2.

A cylinder liner 1 of an internal combustion engine is providedexternally and intermediately its ends with a circumferentiallyextending recess having a depth varying from a minimum value at one endto a maximum value at the opposite end of the liner. In the exampleshown, the recess is of a truncated cone shape having a surface S. Theliner is fitted into the bore in an engine block 2, in such a mannerthat its end having the larger base of said surface S faces the cylinderhead 2a. Thus between the cylinder block 2 and the liner 1, a taperingannular clearance 3 is formed, having a crosssectional area diminishingtowards the cylinder head. The annular clearance 3 extends between alower annular channel 4 and a top annular channel 5, both formed in theengine block.

The outer surface S of the liner 1 is preferably grooved as shown by 1ain a substantially circumferential direction, the grooves being forinstance similar to a screw thread, in order to extend the contactsurface between the liner and oil in the clearance 3.

The depth of grooves 1a and annular cross-sectional area of the gap 3should be conveniently varied along the liner to suit the heat quantityto be removed from "ice the liner, which heat quantity increases towardsthe cylinder head.

This feature is clearly visible in FIG. 3, wherein the depth of thegroove 1a increases from the bottom portion of the liner 1, at which thedepth is pl towards the top portion turned towards the cylinder headbeing at a higher temperature, where the depth is 12, and thecross-sectional area of the clearance 3 diminishes towards said cylinderhead.

A conventional oil pump 6 for the lubricating circuit derives oilthrough a suction conduit 7 and a suction cup 8 provided with a cleanerin the oil sump 9 of the engine, and delivers pressure oil to a conduit10 from which oil flows through a conduit 11 to the engine lubricatingcircuit and through an inlet conduit 19 extending substantially radiallyof the bore in the cylinder block to the lower channel 4 of eachcylinder.

This results in a forced oil flow through the clearance 3 around thecylinder liners 1 which are cooled thereby.

From the top channel 5 of each cylinder oil reaches an outlet conduit 13having interposed therein a pressure adjusting valve 12. A by-pass 18formed with a calibrated bore is arranged around the valve 12 in orderto safely circulate cooling oil even at low numbers of revolution of theengine when the oil pressure is low.

Release valves 17 and an oil cooler 14 are arranged past the valve 12and by-pass 18. The cooler 14 connects through a discharge conduit 16with the oil sump 9 of the engine.

The provision of grooves in the outer liner surface (FIG. 3) increasesthe heat exchange surface and sets the oil in whirling motion, therebyintensifying cooling of the liners by the oil.

The above described device distinguishes by noiseless ness during engineoperation and affords the smallest possible spacing of the walls ofadjacent liners; moreover, the operational temperature is quicklyreached.

With the device the advantages of engines having a sealed coolingcircuit which does not necessitate antifreeze means or the like duringthe cold season and avoids inherent complications and risks of ordinaryor pressure water cooling circuits.

What we claim is:

1. A device for cooling the cylinder liners of internal combustionengines comprising a cylinder block having at least one cylinder boreprovided with a conduit extending substantially radially of the bore ateach end portion of said bore, a cylinder head on said cylinder block, acylinder liner provided externally and intermediately its ends with acircumferentially extending recess having a depth varying from a minimumvalue at one end to a maximum value at the opposite end of said liner,said liner being fitted in the cylinder bore with the shallow end of therecess facing the cylinder head, so that a clearance communicating withsaid conduits is formed between the liner and the cylinder block, one ofsaid conduits being connected to the pressure oil lubricating circuit ofthe engine, the other conduit being connected to a cooler.

2. Cooling device as claimed in claim 1, wherein the surface of therecess in the liner is formed with grooves extending substantiallycircumferentially in order to extend the heat exchange surface of saidliner.

3. Cooling device as claimed in claim 2, wherein the grooves in theliners are of varying depth, the grooves at the deeper end of the recessbeing shallower than the grooves in the shallow end of said recess.

4. Cooling device as claimed in claim 1, wherein the minimumcross-sectional area of said clearance between the liner and thecylinder block is such that at highest engine revolutions the oilflowing therethrough has a speed between 1 and 2 m./sec.

5. Cooling device as claimed in claim 1, wherein an annular channelopened to the cylinder bore is provided in the cylinder block at eachend portion of said cylinder bore, each channel communicating withrespective conduits in the cylinder block.

6. Cooling device as claimed in claim 1, wherein a pressure adjustingvalve is arranged on the connection between one of said conduits in theengine block and the cooler.

References Cited in the file of this patent UNITED STATES PATENTS744,342 Holz Nov. 17, 1903 1,285,430 Sheppy Nov. 19, 1918 2,085,810Ljungstrom July 6, 1937

1. A DEVICE FOR COOLING THE CYLINDER LINERS OF INTERNAL COMBUSTIONENGINES COMPRISING A CYLINDER BLOCK HAVING AT LEAST ONE CYLINDER BOREPROVIDED WITH A CONDUIT EXTENDING SUBSTANTIALLY RADIALLY OF THE BORE ATEACH END PORTION OF SAID BORE, A CYLINDER HEAD ON SAID CYLINDER BLOCK, ACYLINDER LINER PROVIDED EXTERNALLY AND INTERMEDIATELY ITS ENDS WITH ACIRCUMFERENTIALLY EXTENDING RECESS HAVING A DEPTH VARYING FROM A MINIMUMVALUE AT ONE END TO MAXIMUM VALUE AT THE OPPOSITE END OF SAID LINER,SAID LINER BEING FITTED IN THE CYLINDER BORE WITH THE SHALLOW END OF THERECESS FACING THE CYLINDER HEAD, SO THAT A CLEARANCE COMMUNICATING WITHSAID CONDUITS IS FORMED BETWEEN THE LINER AND THE CYLINDER BLOCK, ONE OFSAID CONDUITS BEING CONNECTED TO THE PRESSURE OIL LUBRICAT-